The present invention relates to a strapped down inertial measurement system.
Space reentry vehicles are intentionally caused to spin at high spin rates during portions of the flight mission in order to provide vehicle body stability. Such applications impose stringent requirements on inertial measurement units which include rotation and acceleration sensors. Specifically, such applications impose stringent requirements on the rotation sensors, particularly the rotation sensor generally aligned with the axis about which the vehicle body spins for stabilization. More specifically, stringent requirements are imposed on the scale factor stability of the roll gyro. This is so since scale factor error in the roll gyro will ripple through the resultant attitude data derived from all three gyros including the roll gyro.
Generally, in order to provide gyros which satisfy the stringent requirements on scale factor stability, the roll gyros are particularly tested for scale factor stability at high spin rates. Only those gyros which meet the stringent scale factor stability criteria are than selected for the roll gyro of a particular inertial measurement unit.